1. Field of the Invention
The present disclosure relates to a technique that can recognize a multi-touch operation input by a user.
2. Description of the Related Art
It is conventionally known to detect a plurality of points on an apparatus surface that are simultaneously touched with fingers or styluses and to operate the apparatus based on temporal changes in a plurality of coordinate values of the detected points. In the present disclosure, the above-mentioned technique is referred to as a “multi-touch operation.”
A “rotational operation” is a representative multi-touch operation, which is generally used to cause an object (e.g., an image or a map) displayed on a display unit to rotate around its rotational axis.
As discussed in Japanese Patent Application Laid-Open No. 2011-14169, it is conventionally known to acquire an angle between a line connecting touch points at movement start timing and a line connecting the same touch points at movement completion timing and to identify a rotational operation performed with two instruction positions (i.e., touch points) based on the acquired angle.
However, the angle of a straight line connecting a plurality of touch points may unintentionally change in response to a positional shift of a touch point even when a user does not intend to rotate a displayed object. In such a case, if the movement of a touch point is erroneously recognized as an input of the rotational operation, the apparatus causes the displayed object to rotate around its rotational axis contrary to the user's intent.